Please refer to FIG. 1 that is an exploded perspective view of a waterproof LED illuminating device disclosed in U.S. Pat. No. 7,244,044 granted to the same applicant of the present invention, and to FIG. 2 that is a perspective view of an LED lamp for the waterproof LED illuminating device of FIG. 1. The waterproof LED illuminating device includes an object 10 and an LED lamp bank composed of a plurality of LED lamps 20 serially connected via an electric wire 21. The object 10 is provided with a plurality of through holes 11, and can be a signboard, an LED illuminator or a decorative lighting fixture.
Each of the LED lamps 20 is inserted in one of the through holes 11 on the object 10, and includes an LED 22 and a protective member 23 enclosing a rear part of the LED 22 and the electric wire 21 connected to contact pins of the LED 22, so that the LED 22 and the electric wire 21 are protected against water and the problem of power failure.
Referring to FIG. 2, the protective member 23 has a first end 231 and a second end 232. The LED 22 is forward projected from the first end 231 of the protective member 23. The first end 231 has an end face area smaller than that of the second end 232. In addition, the protective member 23 is wasted. That is, the protective member 23 has a radially inward curved peripheral wall 233, allowing easy insertion of the protective member 23 into the through hole 11 on the object 10.
LED has the advantages of lower cost, less power consumption, and longer usable life compared to the conventional lamps, and can therefore be advantageously used to make signboards, LED illuminators or decorative lighting fixture at low cost. LEDs on the signboard can be arranged to show proper graphic patterns or characters. Moreover, LEDs can be reused when the signboard is changed in design. Therefore, signboards with LEDs are widely adopted among commercial and industrial fields.
However, the LED emits straight light in one direction. In the case of having a large number of LED lamps separately inserted in the through holes on the object, light emitted from any biased LED lamp will show different brightness on the object. That is, the LED lamps being correctly mounted in the through holes on the object are brighter while the LED lamps being angularly mounted in the through holes on the object are darker when viewing from outside of the object. While an auxiliary reflective or refractive hood can be added to the LED lamp to achieve improved uniformity of brightness, such hood will also bring increased manufacturing cost and complicated manufacturing process to the LED lamp.
It is therefore tried by the inventor to develop an improved waterproof LED lamp holding structure, so that all the LED lamps are held immovable and straight in the through holes on an object.